The present invention relates to an image forming apparatus that consumes toner to form an image and a toner consumption calculation method of calculating a toner consumption that is an amount of toner consumed in image formation.
Image forming apparatuses of an electrophotographic process—including printers and multifunction peripherals—extract toner from a toner cartridge to form an image. Some image forming apparatuses can measure an amount of toner consumed during an image formation. In a normal state, the toner consumption is measured (that is, calculated) indirectly from image data, an operation count of a device that contains a toner cartridge, and the like.
On some image forming apparatuses, until the toner consumption reaches a predetermined value, the toner consumption is calculated based on the operation count and an operating time of the device that contains the toner cartridge. After the toner consumption reaches the predetermined value, the toner consumption is henceforth calculated based on the number of dots in the image and data values of the image data.
When calculating the toner consumption based on the operation count and the operating time of the device that contains the toner cartridge, it is possible to accurately calculate the toner consumption when a toner remaining amount is large, but an error is likely to occur when the toner remaining amount becomes small. Further, in the case of calculating the toner consumption based on the number of dots in the image and the data values of the image data, it is difficult to accurately calculate the toner consumption because the toner consumption fluctuates according to contents of the image, variations or changes in reproduction characteristics of toner densities corresponding to the values of the image data, and the like.